Every board on this site is a no-guessing board. From the first click to the last square there is always a square you can prove safe, or a mine you can prove is a mine. This page shows how a board is checked and what we measured, so you can see what that promise rests on.
How a board is checked
- You click first. The mines are placed after that, and none goes on the square you clicked or the eight around it, so the first click always opens an empty region.
- The mines are scattered at random over the rest of the board. Nothing steers them into friendly shapes.
- A solver plays the board from your first click, seeing only the numbers you would see. It uses three rules: a number that already has all its mines (or has exactly as many hidden neighbours as mines) settles its neighbours; two numbers whose squares overlap, compared, settle the squares only one of them touches; and at the end, the count of mines left settles whatever is still hidden.
- If the solver gets stuck anywhere, the whole board is thrown away and the mines are scattered again. Only a board it can finish reaches you.
What the check throws away
| Size | Random boards that need a guess | Boards thrown away per board kept (median / most) | Clicks to clear (3BV), kept / random |
|---|---|---|---|
| Beginner 9×9 | 18% | 0 / 2 | 15 / 15 |
| Intermediate 16×16 | 47% | 0 / 7 | 63 / 63 |
| Expert 30×16 | 95% | 15 / 127 | 170 / 173 |
| Huge 30×30 | 97% | 23 / 179 | 322 / 323 |
Measured on 300 boards per size, 1200 in all. 0 of them ran out of draws before a solvable board was found.
Are no-guessing boards easier?
Not by the measure that counts clicks. On expert, a kept board needs a median of 170 clicks to clear and a random one 173 — the filter removes the coin flip, not the work. What changes is whether skill alone can finish it: 95% of random expert boards reach a point where the three rules cannot decide the next square, and none of the boards here do.
What it does not promise
You can still lose. A misread number, a flag in the wrong place or a slip of the finger opens a mine like anywhere else — the promise is only that a correct reading always exists. And the three rules are the whole definition: a board that needed deeper reasoning than those would be thrown away, even if a stronger player could have found the way through.